Funding for this research was provided by:
the National Key Research and Development Program of China
the China Agriculture Research System
Received: 25 May 2019
Accepted: 10 October 2019
First Online: 24 October 2019
: The clinically ill Jinding ducks were provided by the owners of the ducks. Need for specific ethics approval was waived because the collection of tissue samples from each duck was a part of diagnosis. The Pekin ducklings were provided by Dr. Shuisheng Hou, Institute of Animal Science, Chinese Academy of Agricultural Sciences. All procedures involving animals were conducted following the guidance and under approval of the Animal Welfare and Ethics Committee of China Agricultural University (Approval ID CAU20151102–2) and with the written consent of the Pekin duck owners.
: Not applicable.
: The authors declare that they have no competing interests.